HP exhaust manifold verses Header comparison

[Turboomni]

Factory cast iron manifolds. F.A.S.T. class racing.

 

[Nate S]

It may be application-specific for me experience-wise, but after having had b-body big block cars that
have had both manifolds and headers (either/or), I can state definitely that the ones with headers had
markedly higher temps radiating into the passenger compartment.
Headers are a bunch larger, of course, and all that big tubing being real close to the firewall and footwells
of the passenger compartment meant radiation of heat.
Manifolds are smaller, more compact - and instead of a collection of pipes heading down to a common
collector under your feet down there, the single exhaust pipes coming off the manifold flanges of manifolds
took up less space, had less surface area radiating heat and had more air gap between them and the floors.

Sorry my friend, but I'd bet the farm that at least with big block b-bodies, the amount of heat transmitted
into the passenger compartment from headers is measurably higher than with manifolds.

Yep. It’s radiation, convection and conduction, the only ways heat will move. Let’s say they all start with the same temp exhaust gas and get to the same temp. Headers have more area to radiate, headers have more area to convect. Manifolds have better contact with the head to conduct heat to it. Sure adds up to “headers run hotter” of course when you shut it off they cool down a heck of a lot quicker.

 

[Tim Ziegler]

Put headers on those F.A.S.T. class cars

 

[RJRENTON]

Yep. It’s radiation, convection and conduction, the only ways heat will move. Let’s say they all start with the same temp exhaust gas and get to the same temp. Headers have more area to radiate, headers have more area to convect. Manifolds have better contact with the head to conduct heat to it. Sure adds up to “headers run hotter” of course when you shut it off they cool down a heck of a lot quicker.

TRUE to a certain extent.....but an additional consideration is total surface area. Individual header tubes have considerably more total surface area to radiate, convect heat and considerably less mass than say the Mopar HP manifolds, which would or should appear to exhibit higher losses, plus the noise factor, if that's a consideration. Just an additional thought....
BOB RENTON

 

[Turboomni]

Put headers on those F.A.S.T. class cars

Yes they will go faster. I am using manifolds because it is mainly a street car and frankly I do not need to go as fast as that anyways.

 

[Nate S]

TRUE to a certain extent.....but an additional consideration is total surface area. Individual header tubes have considerably more total surface area to radiate, convect heat and considerably less mass than say the Mopar HP manifolds, which would or should appear to exhibit higher losses, plus the noise factor, if that's a consideration. Just an additional thought....
BOB RENTON

I mentioned the area “headers have more area to radiate...” but yes, same thought.

 

[Tim Ziegler]

I put headers on everything. My 84 Ram Prospector 318 2 BBL, I plumbed the headers into the factory single exhaust which is 2 1/4. I moved the xrossover back 2 to 3 feet for the headers. No cats, factory muffler. 2.9 gears. Its as quiet as when the truck was new and getting 16.5 mpg all around which is 2 mpg better than before the headers

 

[Cudadude2]

My 2 cents. 10:1 451. Factory manifolds intake and exhaust. Runs 11.81 @ 115 with more in it. Totally streetable. If you build to work with manifolds you can get most of what headers offer for a street car.

 

[Tim Ziegler]

But have you tried headers on the combo to compare

 

[Tim Ziegler]

Street Hemis and Ford 406/427 came from the factory with headers...

 

[Nate S]

My 2 cents. 10:1 451. Factory manifolds intake and exhaust. Runs 11.81 @ 115 with more in it. Totally streetable. If you build to work with manifolds you can get most of what headers offer for a street car.

View attachment 1016307

Very cool. For us onlookers, what have you done to get you there? Seems like the headers (if that’s what you happen to want) might get someone to the same place with “less engine” so to speak. That’s certainly fast for a car with manifolds.

 

[Cudadude2]

But have you tried headers on the combo to compare

The engine was designed and built to work with the manifolds. While headers would make some improvement it’s not what it would be with an engine designed to take advantage of them.
B

 

[BSB67]

Very cool. For us onlookers, what have you done to get you there? Seems like the headers (if that’s what you happen to want) might get someone to the same place with “less engine” so to speak. That’s certainly fast for a car with manifolds.

The intake on that motor is a bigger hindrance than the exhaust.

 

[BSB67]

My 2 cents. 10:1 451. Factory manifolds intake and exhaust. Runs 11.81 @ 115 with more in it. Totally streetable. If you build to work with manifolds you can get most of what headers offer for a street car.

View attachment 1016307

Nice!
What is the race weight?

 

[Tim Ziegler]

How exactly is the motor designed to work with manifols as opposed to headers

 

[Kern Dog]

MOST of the guys that choose to run manifolds surely know that their engines will make more power with headers. To those guys, I can see why they choose to stick with the iron. They are absolutely zero maintenance. Install and forget them.
Even though good headers don't leak, rattle or burn out the gaskets frequently, some still stick with manifolds because they either heard that headers are not worth the effort or had a bad experience with headers some time ago.

 

[Tim Ziegler]

and...some who own muscle cars don't have a priority of 'fast' and maybe no plans to dragrace their car. I bought a new 75 360 Duster. Out a the box it ran 15.15. With one change, Hooker race headers and no exhaust system it ran 14.64 at the same dragstrip. I've never had any gasket issues with headers

 

[Tim Ziegler]

Hard to imagine, a new v6 Challenger with A/C, cruise, 4000 pounds, ex mflds are part of head casting, 221 cubic inches and runs the same 1/4 time as a stock 340 Challenger

 

[moparedtn]

Yes - on the whole, headers do better performance-wise on average.

No - that's not the only criteria for making a comparison/decision between them and manifolds
for a lot of folks.

We about done here?

 

[Cudadude2]

Weighs 3520 with me in it.